The present invention relates to an image recording apparatus designed to record a train of parallax images, each having parallax data.
A train of parallax images, each having parallax data, is used to prepare, for example, a stereoscopic which is know as holographic stereogram. A holographic stereogram is prepared in two steps. First, a camera takes many parallax images of an object, each taken at different observation point. Then, the parallax images thus taken, or original images, are recorded in the form of strip- or dot-shaped element holograms, on one hologram-recording medium.
More specifically, a holographic stereogram that has parallax data in respect to horizontal direction only is prepared as will be explained with reference to FIG. 1. First, a strip 301 of parallax images 302 of an object 300 is obtained. The parallax images 302 have been taken at different observation points. Each parallax image 302 has horizontal parallax data. If necessary, the images 302 are subjected to prescribed viewpoint transformation. Then, the parallax images 302 are recorded on a hologram-recording medium 303, in the form of strip-shaped element holograms. Thus, a holographic stereogram having horizontal parallax data is formed.
When an observer looks at the holographic stereogram with one eye, the holographic stereogram appears as a 2-dimensional image that is a collection of the parts of the element holograms. When the observer shifts his or her eye in the horizontal direction, the holographic stereogram appears as a 2-dimensional image that is a collection of the other parts of the element holograms. When the observer looks at the holographic stereogram with both eyes, the two 2-dimensional images are observed, which are slightly different since the eyes are spaced apart in the horizontal direction. As a result, the observer perceives parallax and sees a 3-dimensional (stereoscopic) image of the object 300. Such a holographic stereogram is disclosed in Japanese Patent Application No. 8-172381 (Jpn. Pat. Appln. Laid-open Publication No. 10-20756) and the like.
To prepare a train of parallax images, i.e., original images for such a holographic stereogram, straight or arcuate rails are laid and a camera is moved on the rails at a constant speed by using a pulse motor as drive source. While the camera is being so moved on the rails, it takes pictures of the object, one after another, from different angles. A train of parallax images, each having parallax data, is thereby obtained. The camera must be moved on the rails at a constant speed in the course of acquiring the train of parallax images, so that data showing the position where each picture is taken may be reliably obtained.
However, a complex apparatus is required to move the camera on the rails at a constant speed by means of a pulse motor used as drive source. The cost of preparing a train of parallax images is inevitably very high. Further, the camera as a whole has a large total weight, making it difficult to take pictures of a picture in any given place.
The camera may not be moved on the rails at a constant speed as is desired. Thus, the coordinates of the position where the camera takes a picture may deviate from the coordinates of the desired position of photographing. This results in errors when viewpoint transformation is performed on the train of parallax images. These errors will deteriorate the resultant holographic stereogram in quality.
The present invention has been made in view of the foregoing. The object of the invention is to provide an image recording apparatus that can easily obtain a train of parallax images to be used for preparing prepare a holographic stereogram, without the necessity of laying rails.
An image recording apparatus according to the present invention comprises a camera means and a position-data recording mans. The camera means takes pictures of an object. The position-data recording means records the position data representing the position where the camera means takes each picture.
The camera means may continuously takes a plurality of pictures, one after another, while it is moving with respect to the object. In this case, it is desired that the position-data recording means should record the position data items for all or some of pictures in association with the pictures, respectively. Each position data item represents the position where the camera means took the picture.
The image recording apparatus may further comprise time-data recording means for recording the time when the camera means takes a picture. The camera means may continuously takes a plurality of pictures, one after another, while it is moving with respect to the object. In this case, it is desired that the time-data recording means should record the time data items for all or some of pictures, in association with the pictures, respectively. Each time data item represents the time when the camera means took the picture.
The image recording apparatus may further comprise optical-system data recording means for recording the data about the optical system used in combination with the camera means to take pictures of an object. The means may continuously takes a plurality of pictures, one after another, while it is moving with respect to the object. If this is the case, it is desired that the optical-system data recording means should record the optical-system data items for all or some of pictures, in association with the pictures, respectively.
It is desired that the image recording apparatus further comprise alarm means. The alarm means generates an alarm, either visual or oral message, instructing the operator to move the camera means more slowly and/or start taking pictures again, if the camera mans is moved faster than a predetermined speed while taking pictures.
The image recording apparatus according to the invention can record position data, together with a train of parallax images. Hence, the camera means need not be moved at a constant speed to obtain the parallax images. It is therefore unnecessary to use a drive source, such as a pulse motor, to move the camera means. The apparatus can be therefore simple, light and inexpensive. In addition, no rails are required to guide the camera means. This renders it easy to take pictures of an object.
With the image recording apparatus according to the invention it is possible to determine the coordinates of any position of photographing, even if the camera means moves on the rails at a constant speed. When the images provided by the camera means are processed, generating a train of parallax images for preparing a holographic stereogram, the train of parallax images has no errors and are do not deteriorate in quality.
The image recording apparatus according to the invention can record time data, together with a train of parallax images. Hence, the time-series relation of each frame of image with another frame can be clearly determined. The time-series relation serves as an index in processing an original image to generate a train of parallax images for preparing a holographic stereogram. Further, the standard time data may be recorded, along with the parallax images, so that the time data may be seen in a holographic stereogram.
Still further, the data about the photographing optical system (view-angle data, focal distance data, exposure, diaphragm data, axis-change data, base rotation data, and the like may be recorded, too. In this case, the view angle, for example, need not be calculated and preset before the camera means start taking pictures of the object. It suffices to set parameters for converting images, after the camera means has taken pictures.
Moreover, the motion of the camera means is detected, and an alarm is generated if the camera means moves faster than a predetermined speed. This helps to prevent erroneous photographing. The alarm also instructs the operator to perform photographing again if the photographing first performed is not successful.